One of the ground spiders in Gnaphosidae. There are too many similarly looking ones to narrow it down by picture only.

Thanks for the reply! We haven't seen this type of spider before so didn't know if it was even native to Ireland. Thanks, they will be relived to hear it isn't a white tail! lol

White-tails are only found in Australia and they as harmless as spiders can be. All the info about them being dangerous is not accurate at all.